1. Field of the Invention
The present invention relates to an apparatus for diagnosing and therapeutically treating disease. Particularly, the present invention relates to prostate immobilization and isolation during radiation treatment of prostate cancer. More particularly, the present invention relates to an apparatus that calibrated the position of a rectal balloon for repeated radiation treatment of a prostate. The present invention also relates to devices for repeatedly immobilizing the prostate.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Treatment of prostate cancer using radiation therapy is difficult due to the prostate's position near radiation-sensitive tissues. Treatment is further complicated by prostate motion. Adenocarcinoma of the prostate commonly occurs in the posterior portion of the prostate gland which is in very close proximity to the rectal wall. To plan external beam radiation treatment, urethrograms, CT scans and magnetic resonance imaging (MRI) have all been used to visually localize the prostate, as well as the normal critical structures in the surrounding area.
Typically, the planning of radiation therapy for the treatment of prostate cancer involves the patient undergoing a CT-based simulation scan of the pelvis to determine the location of the prostate gland. In the simulation phase, the patient is placed on CT equipment that is preferably similar to the radiation treatment equipment (except that it does not generate the high, energy radiation beam). The simulation equipment is positioned to simulate the delivery of the sequence of treatment beams prescribed by the treating oncologist. Normally, during the simulation procedure, CT images are acquired. CT images allow the oncologist to locate the position of the tumor and help to facilitate the composition of a radiation treatment plan. The treatment plan delineates the positions of the radiation equipment components for delivery of the treatment beams.
During the actual treatment phase, the patient is placed in the same position on the treatment equipment as in the simulation scans. Radiation-emitting devices are generally known and are used for radiation therapy in the treatment of patients. Typically, a radiation therapy device includes a gantry, which can be swiveled around a horizontal axis of rotation in the course of a therapeutic treatment. A linear accelerator is located in the gantry for generating a high-energy radiation beam. During treatment, the radiation beam is provided by this equipment and is delivered to the patient at the precise location as delineated by the physician during simulation. A further feature of radiation therapy involves portal images, which are commonly used in radiation therapy to verify and record the patient tumor location. Portal images include manual (film) and electronic images (EPI) taken before and/or after the treatment.
During external beam radiation therapy, radiation is directed to the target prostate which is near the rectal wall. A misdirected radiation beam may perforate the rectal wall causing radiation proctitus (rectal bleeding). This toxicity is related to the total radiation dose prescribed and the volume of the anterior rectal wall receiving a high radiation dose. A major factor limiting radiation oncologists' attempts to reduce the volume of the anterior rectal wall receiving a high radiation dose is the position of the prostate gland as well as the intrinsic motion up to 5 millimeters in the anterior to posterior direction caused by rectal peristalsis. Accordingly, oncologists generally will add a margin to the radiation field in order to ensure that the entire prostate gland receives the prescription dose. This margin is typically on the order of 5 to 15 millimeters. As a consequence, lower doses of radiation may need to be used so as not to overexpose radiation sensitive structures. However, this may lead to inadequate radiation treatment and a higher probability of local cancer recurrence.
Various patents and patent publications have issued relating to apparatus for radiation treatment of the prostate. For example, U.S. Pat. No. 5,476,095, issued on Dec. 19, 1995 to Schnall et al., discloses an insertable pickup probe for use in providing diagnostic MRI images. The preferred embodiment is used in imaging the prostate and has an elongated shaft supporting an inflatable patient interface balloon at its distal end. The interface balloon has an inner balloon and an outer balloon, between which a receiving coil is positioned. A lumen for air supply is provided in the shaft for expanding the inner balloon against the outer balloon to place the receiving coil in close proximity to the area of interest in order to provide MRI images.
U.S. patent application Ser. No. 10/211,480, filed on Aug. 2, 2002 to D'Amico et al., discloses an immobilizer probe system and method. This system has an insertable probe for immobilizing a region of interest during staging and radiation therapy thereof. In particular, this device uses a balloon having a rectangular cross section connected to a shaft. The shaft extends to an end of the balloon so as to allow fluid flow through an interior of the shaft and into the balloon so as to selectively inflate the balloon once the balloon is installed into the rectal cavity. The balloon, shaft, and handle are bonded together so that they move radially as a single unit when torque is applied. A syringe is provided which connects the shaft and serves as an air pump to deliver a volume-limited amount of air to the air lumen of the shaft to the balloon. A stop cock is provided to maintain the air within the balloon.
U.S. application Ser. No. 11/623,702, filed on Jan. 16, 2007 by the present inventor, discloses a rectal balloon apparatus that has a shaft with a fluid passageway extending therethrough, a balloon affixed over an end of the shaft such that the fluid passageway communicates with the interior of the balloon, and a sleeve slidably affixed over the shaft. This sleeve is movable between a first position overlying the balloon and a second position away from the balloon. The sleeve has an aperture at an end thereof such that the balloon extends outwardly of this aperture.
U.S. application Ser. No. 11/933,018, filed on Oct. 31, 2997 by the present inventor, is a continuation-in-part of U.S. application Ser. No. 11/623,702. This application additionally describes the balloon as having a laterally flat surface thereon when inflated. There is a longitudinal groove extending along the laterally flat surface. Together, the laterally flat surface and the groove enhance the seating of the prostate on the balloon. Additionally, the application describes a valve assembly on the end of the shaft opposite the balloon. A fluid introducing means is removably attached to the valve assembly to introduce fluid into the valve assembly and move the balloon from the non-inflated condition to the inflated condition.
U.S. patent application Ser. No. 11/966,544, filed on Dec. 28, 2008 by the present inventor, discloses a rectal balloon apparatus has a shaft with a fluid passageway extending therethrough. A balloon is affixed over an end of the shaft such that the fluid passageway communicates with an interior of the balloon. A lumen extends along the shaft so as to allow bodily gas pressure to pass therethrough. The balloon has a laterally flat surface thereon when inflated. A sleeve is positioned over a portion of the shaft. The lumen is affixed to a surface of the sleeve. The sleeve has a first portion and a second portion frangibly connected together.
A problem associated with the use of prostate immobilizers, i.e. rectal balloon apparatus, is that the immobilizers must be repeatedly positioned near the prostate over the course of many treatments. Insertion techniques can vary greatly between treatments. This can cause a change in the depth of the inserted balloon. The patient can often squeeze the sphincter muscles during insertion and treatment. This can also change the position of the balloon. This can result in different positionings of the balloon, and a variation of the immobilized prostate's position, and the tissues surrounding the prostate, such that radiation treatment from session to session is not as exact as it should be. Thus, there is a need for a device that can repeatably position a prostate immobilizer for accurate radiation treatment of a prostate over multiple sessions.
Another problem associated with prostate immobilizers is that the positioning of the immobilizer can be a matter of guesswork by the hospital personnel involved. Thus, there is a need for more precise positioning of the prostate immobilizers.
U.S. patent Ser. No. 12/141,270, filed on Jun. 18, 2008 by Isham, discloses a rectal balloon apparatus has a shaft with a fluid passageway extending therethrough. A balloon is affixed over an end of the shaft such that the fluid passageway communicates with an interior of the balloon. The balloon has a laterally flat surface thereon when inflated. The laterally flat surface of the balloon has a longitudinal groove formed thereon. The balloon has a radiation sensor positioned within the groove and a plurality of fiducial markers positioned on a surface of the balloon. A stopper is slidably mounted on the shaft. When it is desired to measure the radiation dose by the radiation sensor, it is imperative that the accurate positioning be achieved. The radiation sensor achieves maximum accuracy and effectiveness when it positioned accurately in the same position during radiation treatment.
It is an object of the present invention to provide a device for a prostate immobilizer whereby the position of the balloon can be easily ascertained by medical personnel.
It is another object of the present invention to provide a device for a prostate immobilizer that allows medical personnel to re-position the apparatus in substantially the same orientation in successive treatment sessions.
It is another object of the present invention to provide a device for a prostate immobilizer that is easy to use and easy to install.
It is another object of the present invention to provide a prostate immobilizer which maximizes the comfort of the patient.
It is another object of the present invention to provide a prostate immobilizer which enhances the ability to properly seat the prostate on a flat surface of the rectal balloon.
It is another object of the present invention to provide a prostate immobilizer which avoids potential allergic reactions.
It is still another object of the present invention to provide a prostate immobilizer which is easy to manufacture and relatively inexpensive.
It is still another object of the present invention to provide a prostate immobilizer which has improved holding stability when inflated.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.